On Twitter, users shared photos and videos of what parts of Houston looked like before and after the flood, including roads, bridges and interstate highways. The before and after images show the magnitude of the devastation.

And Houston is bracing for even more flooding as forecasters say an additional 30 inches of rain could fall in southeast Texas before the slow-moving storm departs.

“Catastrophic flooding in the Houston metropolitan area is expected to worsen,” the National Weather Service said Sunday. “This event is unprecedented, and all impacts are unknown and beyond anything experienced.”